Protection of the environment from ionising radiation in a regulatory context (PROTECT): Assessment approaches – practicality, relevance and merits

Abstract

Abstract. In common with the assessment of chemical stressors many of the methods used for the assessment of risk of non-human biota exposed to radiation use tiered approaches. The initial tier within these approaches is designed to be simple and conservative with the aim to identify sites of negligible concern which can be excluded from more detailed assessment with a high degree of confidence. In this paper we compare the outputs of the screening tiers of three tools which are freely available as software packages. Outputs were compared for terrestrial and freshwater ecosystems assuming 1 Bq per unit media. Considerable variability between the risk quotients (RQ) estimated by the three approaches used was seen for some radionuclide-organism-ecosystem combinations. Reasons for this are explored with differences in transfer parameters used by the models being a common contributor. The large variation within RQ values estimated by the approaches requires further investigation as it does not promote the level of confidence required by the user. The practicalities of applying a single generic screening dose rate in assessments are also explored.

Protection of the environment from ionising radiation in a regulatory context (protect): proposed numerical benchmark values

“…In many cases, the highest exposure is likely to be estimated for a comparatively radioinsensitive organism. For example, for 59 of the 63 radionuclides considered within the ERICA Tool (Brown et al, 2008), invertebrate organisms, plants or phytoplankton are the limiting freshwater organisms (Beresford et al, 2009). Conversely, vertebrates, which are generally considered to be the most radiosensitive organisms, are comparatively rarely identified as the limiting organism because they are less exposed.…”

Protection of the environment from ionising radiation in a regulatory context—an overview of the PROTECT coordinated action project

“…However, a problem with the use of a single generic screening value in radiological risk assessments for wildlife is that the most exposed organisms may not be the most radiosensitive. For instance, when applying a generic screening dose rate of 10 µGy h −1 , of 63 radionuclides considered within the ERICA Tool vertebrate organisms are only rate limiting in 4 instances for the freshwater ecosystem, 19 in the terrestrial ecosystem and 7 in the marine ecosystem (Beresford et al 2009(Beresford et al , 2010a. The application of a generic screening value may result in either (i) overly conservative assessments which lead to more detailed site specific assessments which are unwarranted or (ii) assessments which do not identify the need for more detailed consideration of the more radiosensitive wildlife groups.…”

“…Such tiered assessments begin with a highly conservative 'screening tier' and progress, if required, to more refined assessments. Whilst 20 approaches were considered (Beresford et al 2008c), we concentrated on evaluating the three most comprehensive which are freely available to any users: RESRAD-BIOTA (implementing the USDOE graded approach (USDoE 2002)), Environment Agency R&D128 (developed for use in England and Wales for assessment of Natura 2000 13 sites, Copplestone et al 2001Copplestone et al , 2003 and the ERICA Tool (Brown et al 2008).…”

Protection of the environment from ionising radiation in a regulatory context (PROTECT): Review of current regulatory approaches to both chemicals and radioactive substances

“…The information in this paper is contributing to other PROTECTs activities to determine the appropriateness of numeric benchmarks suggest for use to demonstrate environmental protection from the effects of ionising radiation and to address the issues of the cost, or burden, of any environmentally derived regulation [5,6]. The overall outputs from the PROTECT project will contribute to the debate on the environmental consequences of our use of radioactive substances.…”

“…It is also important that approaches used are practicable, credible to stakeholders and fit for purpose [5].…”